Evaluation of the Fit and Accuracy of Conventional and CAD/CAM Removable Partial Denture Frameworks Using Different Manufacturing Techniques and Materials

Abstract

Statement of problem. The use of computer-aided design and computer aided manufacturing (CAD/CAM) technology continues to increase in removable partial denture fabrication. To date, few studies have evaluated the fit and accuracy of conventional and CAD/CAM removable partial dentures (RPDs) using different manufacturing techniques and materials. Purpose. The purpose of this in vitro study was to compare the fit and accuracy of conventional versus CAD/CAM fabricated RPD frameworks using cast cobalt-chromium (Co-Cr) alloy, SLM cobalt-chromium (Co-Cr) alloy, milled aryl ketone polymer (AKP), and milled modified polyetheretherketone (PEEK). Materials and Methods. A total of 4 groups of 10 samples in each group were included in this study, for a total of 40 samples (n=40). Fit and accuracy of conventional and CAD/CAM fabricated RPD frameworks using different materials including cobalt-chromium (Co-Cr) alloy, aryl ketone polymer (AKP), and modified polyetheretherketone (PEEK) were evaluated using digital superimposition. Analysis of variance (Kruskall-Wallis) was conducted with a significance level of α=0.05 to determine whether the differences between each processing methods were statistically significant. Scheffe post-hoc test was used to compare the overall accuracy and fit among the different groups. Results. Color mapping revealed statistically significant differences between the conventionally cast Co-Cr framework group versus the SLM Co-Cr framework, milled AKP framework, and 2 milled PEEK framework groups with less overall gap with the conventional cast Co-Cr framework group. The most significant gap (0.63mm ± 0.08mm) was observed with the Anterior strap of the major connector. Conclusion. Within the limitation of the present study, the cast cobalt-chromium (Co-Cr) RPD framework revealed better fit when compared with SLM cobalt-chromium (Co-Cr), milled aryl ketone polymer (AKP), and milled modified polyetheretherketone (PEEK) frameworks. Milled Aryl Ketone Polymer and milled modified polyetheretherketone RPD frameworks revealed better fit when compared with SLM cobalt-chromium (Co-Cr) RPD framework. Retentive arms and the rest showed better fit when compared with anterior and the posterior strap of the major connector, the reciprocal arm, and the guiding plates among all tested groups. Anterior strap of the major connector had the greatest discrepancy among all tested groups. Clinical Implications. The overall fit and accuracy of both conventional and CAD/CAM removable partial dentures (RPDs) using different manufacturing techniques and materials were clinically acceptable.